electrical issues - instruments, headlights, fog lights

[lgb240]

Hi everyone,

I'm hoping the collective wisdom from the forum can help me diagnose an electrical glitch. I have an '87 3.2 Carrera, and I believe the previous owner has done some subtle wiring changes to control the fog lights differently than the stock configuration.

Right now, here's a quick run down of what's working / not working:

Situation 1- Ignition on
The instrument lights are on, even though headlight and fog light switch is off

Situation 2 -Ignition on, headlight switch to first on position
Instruments lights are on, rotating headlight switch dims them, no outside lights are on. Switching on the foglight switch turns on the fog lights. No other outside lights are on at this point.

From the owners manual, the first on position for the headlight switch should turn on the parking lights, this isn't happening on my car.

Situation 3- Ignition on, Headlight switch pulled out to second on position
Instruments lights go out, rotating headlight switch does nothing to the instruments lights, headlights, parking lights are on, high beams can be controlled at the stalk, fog lights go out.

Situations 1 and 3 are what I need to overcome. I'm guessing that the instruments lights shouldn't be on with ignition power only. I would also be nice to drive at night with the instruments lit up. I'm suspecting something was manipulated with the wiring at the headlight switch; the fuse panel seems to be as it should. I've read a few threads about fog lights as daytime running lights, but the always on instrument lights, then completely off when the headlights are on are throwing me for a loop. Electrical isn't one of my comfort zones...

Any help would be appreciated ...

[Grady Clay]

Yikes!

Probably the first thing to do is carefully look for non-Factory wiring.

Look behind the dash at the backs of the ignition switch and headlight switch.
Look at the fuse/relay panel in the trunk.
Look under the cowl from the trunk (remove carpet and panel).
Follow the fog light wires back from the lights.
Inspect the wiring to the headlights.

Someone here has the Factory Workshop Manual current flow diagrams for your 911.
Pelican only has them for ’82:
Pelican Parts - Porsche 911 Parts Listings & Diagrams
but these will get you started as there shouldn’t be too much difference.
(But don’t change anything without the ’87 version.)

This may be only one wire inappropriately moved so tread carefully.

Best,
Grady

[rusnak]

I think someone changed the headlight and/or ignition switches and did not use careful notes.

[DRACO A5OG]

OMG what a freakin nightmare, sorting out buddy's '86 wiring.

His front side marker came on when he pressed the brakes, at night when he turned on the headlights his brake lights including his 3rd light remained on. It distorted his lenses (melt???)

Anywho we fixed 99% now his right rear side marker is out, another weekend story.

+1 on Grady's suggestion get the wiring diagram, remember top of panel is power input, bottom goes to the components. Just go slow and a fuse block at a time.

Also search for thread from "Gerry" aka 86 911 Targa, he thoroughly explains the wiring and recommended fuses mods.

Jim

[DRACO A5OG]

Nevermind found him for you: Added fuses & relays.

Compliments of Gerry:

[rusnak]

Oh my....that is golden!

[DRACO A5OG]

Gerry helped me so much beyond call of duty when I re-wired my fog light to DLR's, so thorough, sometimes scary thorough.

He is a freakin Awesome Pelican!

[crustychief]

87 version.

[lgb240]

Problem solved !!!

Many thanks to everyone - that pic of the back of the headlight switch saved the day. Very easy fix.

I know I don't need to say it but I will ... this forum rocks!!

Happy days and thanks again,

lgb240

[DRACO A5OG]

Thanks to Pelicans like Gerry aka 86 911 Targa!

Now enjoy!